1. Chapter 14: Queue and Priority Queue Implementations
CS Data Structures
Mehmet H Gunes
Modified from authors’ slides

2. Implementations of the ADT Queue
Like stacks, queues can have
Array-based or
Link-based implementation
Can also use implementation of ADT list
Efficient to implement
Might not be most time efficient as possible
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3. An Implementation That Uses the ADT List
An implementation of the ADT queue that stores its entries in a list
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4. An Implementation That Uses the ADT List
The header file for the class ListQueue
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5. An Implementation That Uses the ADT List
The header file for the class ListQueue
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6. An Implementation That Uses the ADT List
The implementation file for the class ListQueue
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7. An Implementation That Uses the ADT List
The implementation file for the class ListQueue
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8. An Implementation That Uses the ADT List
The implementation file for the class ListQueue
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9. A Link-Based Implementation
Similar to other link-based implementation
One difference … Must be able to remove entries
From front
From back
Requires a pointer to chain’s last node
Called the “tail pointer”
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10. A Link-Based Implementation
A chain of linked nodes with head and tail pointers
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11. A Link-Based Implementation
The header file for the class LinkedQueue
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12. A Link-Based Implementation
The header file for the class LinkedQueue
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13. A Link-Based Implementation
Adding an item to a nonempty queue
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14. A Link-Based Implementation
Removing an item from a queue of more than one item
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15. A Link-Based Implementation
Removing an item from a queue of more than one item
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16. A Link-Based Implementation
A circular chain of linked nodes with one external pointer
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18. An Array-Based Implementation
A naive array-based implementation of a queue for which rightward drift can cause the queue to appear full
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19. An Array-Based Implementation
A circular array as an implementation of a queue
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20. An Array-Based Implementation
The effect of three consecutive operations on the queue
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21. An Array-Based Implementation
front and back as the queue becomes empty and as it becomes full
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22. An Array-Based Implementation
front and back as the queue becomes empty and as it becomes full
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23. An Array-Based Implementation
The header file for the class ArrayQueue
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24. An Array-Based Implementation
The implementation file for the class ArrayQueue
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25. An Array-Based Implementation
The implementation file for the class ArrayQueue
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26. An Array-Based Implementation
The implementation file for the class ArrayQueue
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27. An Array-Based Implementation
The implementation file for the class ArrayQueue
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28. An Array-Based Implementation
A circular array having one unused location as an implementation of a queue
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29. Comparing Implementations
Issues
Fixed size (array-based) versus
dynamic size (link-based)
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30. An Implementation of the ADT Priority Queue
A header file for the class SL_PriorityQueue.
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31. An Implementation of the ADT Priority Queue
A header file for the class SL_PriorityQueue.
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